package tests;

import javax.swing.plaf.synth.SynthEditorPaneUI;
import java.util.Scanner;

public class test4 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] ch = new int[n+1];
        ch[1]=1;
        ch[2]=1;
        for(int i=3;i<=n;i++){
            ch[i]=ch[i-1]+ch[i-2];
        }
        System.out.println(ch[n]);
        return;
    }
}
